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Science (English Medium) Class 11 - CBSE Question Bank Solutions

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Match the compounds given in Column I with their uses mentioned in Column II.

Column I Column II
(i) CaCO3 (a) Dentistry, ornamental work
(ii) Ca(OH)2 (b) Manufacture of sodium carbonate from caustic soda
(iii) CaO (c) Most negative E value among alkali O metals.
(iv) CaSO4 (c) Manufacture of high-quality paper
  (d) Used in white washing
[10] S-block Elements (Alkali and Alkaline Earth Metals)
Chapter: [10] S-block Elements (Alkali and Alkaline Earth Metals)
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Match the elements given in Column I with the colour they impart to the flame given in Column II.

Column I Column II
(i) Cs (a) Apple green
(ii) Na (b) Violet
(iii) K (c) Brick red
(iv) Ca (d) Yellow
(v) Sr (e) Crimson red
vi) Ba (f) Blue
[10] S-block Elements (Alkali and Alkaline Earth Metals)
Chapter: [10] S-block Elements (Alkali and Alkaline Earth Metals)
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Boric acid is an acid because its molecule ______.

[11] Some P-block Elements
Chapter: [11] Some P-block Elements
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Draw the structures of BCl3.NH3 and AlCl3 (dimer).

[11] Some P-block Elements
Chapter: [11] Some P-block Elements
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Explain the nature of boric acid as a Lewis acid in water.

[11] Some P-block Elements
Chapter: [11] Some P-block Elements
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Draw the structure of boric acid showing hydrogen bonding. Which species is present in water? What is the hybridisation of boron in this species?

[11] Some P-block Elements
Chapter: [11] Some P-block Elements
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When aqueous solution of borax is acidified with hydrochloric acid, a white crystalline solid is formed which is soapy to touch. Is this solid acidic or basic in nature? Explain.

[11] Some P-block Elements
Chapter: [11] Some P-block Elements
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What are boranes? Give chemical equation for the preparation of diborane.

[11] Some P-block Elements
Chapter: [11] Some P-block Elements
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A compound (A) of boron reacts with NMe3 to give an adduct (B) which on hydrolysis gives a compound (C) and hydrogen gas. Compound (C) is an acid. Identify the compounds A, B and C. Give the reactions involved.

[11] Some P-block Elements
Chapter: [11] Some P-block Elements
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The increasing order of reduction of alkyl halides with zinc and dilute HCl is ______.

[9] Hydrocarbons
Chapter: [9] Hydrocarbons
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Write the structures and names of products obtained in the reactions of sodium with a mixture of 1-iodo-2-methylpropane and 2-iodopropane.

[9] Hydrocarbons
Chapter: [9] Hydrocarbons
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Match the hydrocarbons in Column I with the boiling points given in Column II.

Column I Column II
(i) n-Pentane (a) 282.5 K
(ii) iso-Pentane (b) 309 K
(iii) neo-Pentane (c) 301 K
[9] Hydrocarbons
Chapter: [9] Hydrocarbons
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896 mL vapour of a hydrocarbon ‘A’ having carbon 87.80% and hydrogen 12.19% weighs 3.28 g at STP. Hydrogenation of ‘A’ gives 2-methylpentane. Also ‘A’ on hydration in the presence of H2SO4 and HgSO4 gives a ketone ‘B’ having molecular formula C6H12O. The ketone ‘B’ gives a positive iodoform test. Find the structure of ‘A’ and give the reactions involved.

[9] Hydrocarbons
Chapter: [9] Hydrocarbons
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An unsaturated hydrocarbon ‘A’ adds two molecules of H2 and on reductive ozonolysis gives butane-1,4-dial, ethanal and propanone. Give the structure of ‘A’, write its IUPAC name and explain the reactions involved.

[9] Hydrocarbons
Chapter: [9] Hydrocarbons
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Which of the following statements is wrong?

[14] Environmental Chemistry
Chapter: [14] Environmental Chemistry
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Which of the following statements is correct?

[14] Environmental Chemistry
Chapter: [14] Environmental Chemistry
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Ozone is a toxic gas and is a strong oxidising agent even then its presence in the stratosphere is very important. Explain what would happen if ozone from this region is completely removed?

[14] Environmental Chemistry
Chapter: [14] Environmental Chemistry
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On the basis of chemical reactions involved, explain how do chlorofluorocarbons cause thinning of ozone layer in stratosphere.

[14] Environmental Chemistry
Chapter: [14] Environmental Chemistry
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How is ozone produced in stratosphere?

[14] Environmental Chemistry
Chapter: [14] Environmental Chemistry
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Ozone is a gas heavier than air. Why does ozone layer not settle down near the earth?

[14] Environmental Chemistry
Chapter: [14] Environmental Chemistry
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